A vibration generator is used as a pager in portable information apparatuses such as cellular phones. A conventional vibration generator has employed a cylindrical motor equipped with an unbalancing weight. However, the cylindrical motor has a ceiling of being slimmed down, and is hard to be mounted onto a board by an automatic mounting machine. A coin-shaped motor equipped with an unbalancing weight is commercialized for overcoming the foregoing problems; however, its vibrating direction is in parallel with the printed circuit board, so that the vibration is hard to be sensed. A button-shaped vibration linear actuating device is proposed in order to generate vibrations vertical to the board; however, a greater exciting force cannot compatible with a slimmer body. A conventional vibration linear actuating device, in general, employs a push-pull driving circuit using four switching elements. This is disclosed in Japanese Patent Application Non-examined Publication No. 2001-25706.
FIG. 15 shows a circuit diagram of the conventional actuating device. Starter 61, output controller 62, driving-pulse setter 63, and driver 64 formed of four switching elements Q11-Q14 coupled together into a bridge structure. Coil 65 of the vibration actuating device is coupled to a middle point of the bridge structure, and driver 64 drives coil 65. This actuating device has numbers of elements in the driving circuit, and a movement of the mover along a positive direction or a negative direction needs to be powered every time. Thus the foregoing structure needs complicated control and consumes a lot of power.
There are other prior art disclosed in PCT International Publication No. WO99/40673, Japanese Patent Application Non-Examined Publication Nos. 2000-14190 and H11-0.197601. The present invention discloses a vibration linear actuating device, a method of driving the same device, and a portable information apparatus employing the same device that has a novel structure different from those prior art.